Internal combustion engine with exhaust with gas recirculation

Abstract

Supercharged internal combustion engine with exhaust recirculation, in which the exhaust manifold of the engine communicates, via non-return valves and an exhaust conduit, with the inlet manifold of the engine. The non-return valves are arranged to only open when the exhaust pressure in the exhaust manifold is higher than the charged air pressure.

What is claimed is:  
     
       1. Internal combustion engine, comprising an inlet manifold ( 3 ) and an exhaust manifold ( 2 ), respectively, opening into inlet ducts and exhaust ducts, respectively, to the engine cylinders, a charging unit ( 6 ), the pressure side ( 8 ) of which is connected to an inlet air conduit ( 9 ) opening into the inlet manifold; and a conduit ( 17   a ,  17   b ,  19 ) for recirculation of exhaust from the exhaust side of the engine to its inlet side, characterized in that the recirculation conduit ( 17   a ,  17   b ,  19 ) communicates with valve means ( 16   a, b ;  40   a, b ) which are connected directly to the exhaust manifold and that valve control means ( 13 ) are arranged, during such operating conditions where the exhaust is to be recirculated, to only Permit the valve means to open when the exhaust pressure in the manifold ( 2 ) is higher than the air pressure on the pressure side of the charging unit ( 6 ), and 
       characterized in that the exhaust manifold ( 2 ) is divided into at least two branch portions ( 2   a, b ) which open into a common exhaust pipe ( 4 ), and that the valve means comprise one valve ( 16   a, b ;  40   a, b ) in each branch portion.  
     
     
       2. In an internal combustion engine having an inlet side with an inlet manifold opening to an inlet duct, an exhaust side with an exhaust manifold opening to an exhaust duct, a charging unit having a pressure side that communicates with the inlet duct, and a recirculation conduit that recirculates exhaust from the exhaust side to the inlet side, the improvement wherein the recirculation conduit communicates with a valve that opens directly into the exhaust manifold only when a pressure in the exhaust manifold exceeds a pressure in the pressure side of the charging unit. 
     
     
       3. Internal combustion engine, comprising an inlet manifold ( 3 ) and an exhaust manifold ( 2 ), respectively, opening into inlet ducts and exhaust ducts, respectively, to the engine cylinders, a charging unit ( 6 ), the pressure side ( 8 ) of which is connected to an inlet air conduit ( 9 ) opening into the inlet manifold; and a conduit ( 17   a ,  17   b ,  19 ) for recirculation of exhaust from the exhaust side of the engine to its inlet side, characterized in that the recirculation conduit ( 17   a ,  17   b ,  19 ) communicates with valve means ( 16   a, b ;  40   a, b ) which are connected directly to the exhaust manifold and that valve control means ( 13 ) are arranged, during such operating conditions where the exhaust is to be recirculated, to only permit the value means to open when the exhaust pressure in the manifold ( 2 ) is higher than the air pressure on the pressure side of the charging unit ( 6 ). 
     
     
       4. Internal combustion engine according to claim  3 , characterized in that the recirculation conduit ( 17   a, b ,  19 ) communicates with the inlet side via a cooler ( 18 ). 
     
     
       5. Internal combustion engine according to claim  4 , characterized in that the exhaust manifold ( 2 ) is divided into at least two branch portions ( 2   a, b ) which open into a common exhaust pipe ( 4 ), and that the valve means comprise one valve ( 16   a, b ;  40   a, b ) in each branch portion. 
     
     
       6. Internal combustion engine according to claim  3 , characterized in that said valve means are formed of at least one non-return valve ( 16   a ,  16   b ) which is arranged to open for exhaust recirculation when the exhaust pressure in the manifold ( 2 ) is higher than the inlet air pressure. 
     
     
       7. Internal combustion engine according to claim  6 , characterized in that the recirculation conduit ( 17   a, b ,  19 ) communicates with t he inlet side via a cooler ( 18 ). 
     
     
       8. Internal combustion engine according to claim  6 , characterized in that the exhaust manifold ( 2 ) is divided into at least two branch portions ( 2   a, b ) which open into a common exhaust pipe ( 4 ), and that the valve means comprise one valve ( 16   a, b ;  40   a, b ) in each branch portion. 
     
     
       9. Internal combustion engine according to claim  3 , characterized in that said valve means are formed of at least one solenoid valve ( 40   a ,  40   b ), which is controlled by a control unit ( 13 ), which is arranged, depending on engine data fed to the control unit, to open the valve when the exhaust pressure in the manifold ( 2 ) is higher than the inlet air pressure. 
     
     
       10. Internal combustion engine according to claim  9 , characterized in that the recirculation conduit ( 17   a, b ,  19 ) communicates with the inlet side via a cooler ( 18 ). 
     
     
       11. Internal combustion engine according to claim  9 , characterized in that the exhaust manifold ( 2 ) is divided into at least two branch portions ( 2   a, b ) which open into a common exhaust pipe ( 4 ), and that the valve means comprise one valve ( 16   a, b ;  40   a, b ) in each branch portion.